Ship & Naval

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The largest of the Navy"s five systems

The largest of the Navy"s five systems commands, Naval Sea Systems Command (NAVSEA) maintains the current Navy, acquires the next Navy and designs the Navy after next. Accounting for nearly one-fifth of the Navy"s budget, NAVSEA manages more than 150 acquisition programs and has 33 activities in 16 states. With a force of 53,000 civilian, military and contract support personnel, NAVSEA engineers, builds, buys and maintains the Navy"s ships and submarines and their combat systems.

The origin of NAVSEA dates to 1794, when Commodore John Barry was charged to oversee the construction of a 44-gun frigate and ensure that all business "harmonized and conformed" to the public"s interest. NAVSEA strives to be an efficient provider of defense resources for the nation, and it plays an important role in the Navy Enterprise.

As a Provider Command, it has the responsibility of directing resources from resource sponsors into the proper mix of manpower and resources to properly equip the Fleet. NAVSEA manages foreign military sales cases that include billions of dollars in annual military sales to partner nations. NAVSEA has the further responsibility of establishing and enforcing technical authority in combat system design and operation. These technical standards use the organization"s technical expertise to ensure systems are engineered effectively, and that they operate safely and reliably. NAVSEA is organized into headquarters directorates and five affiliated Program Executive Offices."



NAVSO NCIS Agent Gets Superior Civilian Service Award

Source: www.navy.mil

NAVSO NCIS Agent Gets Superior Civilian Service Award
Story Number: NNS071224-01
Release Date: 12/24/2007 4:58:00 PM
By Mass Communication Specialist 3rd Class Alan Gragg, U.S. Naval Forces Southern Command Public Affairs

MAYPORT, Fla. (NNS) -- Naval Criminal Investigative Service (NCIS) Special Agent Daniel Gilbride received the Navy Superior Civilian Service Award at U.S. Naval Forces Southern Command (NAVSO) Headquarters Dec. 19.

NAVSO Commander, Rear Adm. James W. Stevenson Jr., presented Gilbride with the award on behalf of Secretary of the Navy Donald Winter during a short ceremony and citation.

Gilbride received the award for his outstanding work as the NCIS Liaison to NAVSO from December 2006 to January 2008. Gilbride was cited as having "excelled during his tenure, far exceeding command expectations concerning criminal investigative, counterterrorism and counter-intelligence support."

"Special Agent Gilbride"s contributions to the safety and security are immeasurable," said Stevenson. "I am pleased to be able to give this small thanks to him on behalf of the U.S. Navy."

Gilbride participated in numerous force protection detachments" site surveys throughout NAVSO"s area of focus, providing over 40 counter-intelligence and counter-terrorism updates to the staff while liaising with national and international agencies in support of NAVSO"s mission.

He coordinated NCIS support for the 2007 multi-national Partnership of the Americas deployment, USNS Comfort (T-AH 020) humanitarian assistance deployment and the Global Fleet Station deployment.

Gilbride represented NAVSO at the highest national levels during multiple high-profile counter-terrorism investigations, and provided expert coordination between the command and law enforcement authorities in multiple cases under civilian jurisdiction, ensuring NAVSO received timely updates on case disposition.

"It has been a privilege to serve as NCIS"s representative to NAVSO during such a key period in our Navy"s relations with our Latin American neighbors," said Gilbride. "Hard work by the deployed NCIS agents supporting Mayport based vessels was the key to the success of our team."



Propulsion

[edit] Pre-mechanisation

Ships of the world in 1460, according to the Fra Mauro map.
Ships of the world in 1460, according to the Fra Mauro map.

Until the application of the steam engine to ships in the early 19th century, oars propelled galleys or the wind propelled sailing ships. Before mechanisation, merchant ships always used sail, but as long as naval warfare depended on ships closing to ram or to fight hand-to-hand, galleys dominated in marine conflicts because of their maneuverability and speed. The Greek navies that fought in the Peloponnesian War used triremes, as did the Romans contesting the Battle of Actium. The use of large numbers of cannon from the 16th century meant that maneuverability took second place to
broadside weight; this led to the dominance of the sail-powered warship.

[edit] Reciprocating steam engines

The development of piston-engined steamships was a complex process.
Early steamships were fueled by wood, later ones by coal or fuel oil.
Early ships used stern or side paddle wheels, later ones used screw
propellers.

The first commercial success accrued to Robert Fulton"s North River Steamboat (often called Clermont) in the US in 1807, followed in Europe by the 45-foot Comet of 1812. Steam propulsion progressed considerably over the rest of the
19th century. Notable developments included the steam surface condenser,
which eliminated the use of sea water (salt water) in the ship"s
boilers. This permits higher steam pressures, and thus the use of
higher efficiency multiple expansion (compound) engines. As the means
of transmitting the engine"s power, paddle wheels gave way to more efficient screw propellers.

[edit] Steam turbines

Steam turbines were fueled by coal or later, fuel oil, or nuclear power. The marine steam turbine developed by Sir Charles Algernon Parsons, raised the power to weight ratio. He achieved publicity by demonstrating it unofficially in the 100-foot Turbinia at the Spithead naval review in 1897. This facilitated a generation of high-speed liners in the
first half of the 20th century and rendered the reciprocating steam
engine obsolete, first in warships, and later in merchant vessels.

In the early 20th century, heavy fuel oil came into more general use and began to replace coal as the fuel of choice in steamships. Its great advantages were
convenience, reduced manning due to removing the need for trimmers and
stokers, and reduced space needed for fuel bunkers.

In the second half of the 20th century, rising fuel costs almost led
to the demise of the steam turbine. Most new ships since around 1960
have been built with diesel engines. The last major passenger ship built with steam turbines was the Fairsky,
launched in 1984. Similarly, many steam ships were re-engined to
improve fuel efficiency. One high profile example was the 1968 built Queen Elizabeth 2 which had her steam turbines replaced with a diesel-electric propulsion plant in 1986.

Most new-build ships with steam turbines are specialist vessels such
as nuclear-powered vessels, and certain merchant vessels (notably Liquefied Natural Gas (LNG) and coal carriers) where the cargo can be used as bunker fuel.

[edit] LNG carriers

New LNG carriers (a high growth area of shipping) continue to be built with steam turbines. The natural gas is stored in a liquid state in cryogenic vessels aboard these ships, and a small amount of "boil off" gas is
needed to maintain the pressure and temperature inside the vessels, to
within operating limits. The "boil off" gas provides the fuel for the
ship"s boilers, which provide steam for the turbines, the simplest way
to deal with the gas. Technology to operate internal combustion engines (modified marine two stroke diesel engines)
on this gas has improved however, so such engines are starting to
appear in LNG carriers; with their greater thermal efficiency, less gas
is burnt. Also, developments have been made in the process of
re-liquefying "boil off" gas, letting it be returned to the cryogenic
tanks. The financial returns on LNG are potentially greater than the
cost of the marine grade fuel oil burnt in conventional diesel engines,
so the re-liquefaction process is starting to be used on diesel engine
propelled LNG carriers. Another factor driving the change from turbines
to diesel engines for LNG carriers is the shortage of steam turbine
qualified sea going engineers. With the lack of turbine powered ships
in other shipping sectors, and the rapid rise in size of the worldwide
LNG fleet, not enough have been trained to meet the demand. It may be
that the days are numbered for the last stronghold for steam turbine
propulsion systems, despite all but sixteen of the orders for new
carriers at the end of 2004 being for steam turbine propelled ships. [1]

[edit] Nuclear-powered steam turbines

In these vessels, the reactor heats steam to drive the turbines. Partly due to concerns about safety
and waste disposal, nuclear propulsion has become usual only in
specialist vessels. In large aircraft carriers, the space formerly used for ship"s bunkerage could be used instead to bunker aviation fuel. In submarines, the ability to run submerged at high speed and in relative quiet for long periods holds obvious advantage. A few cruisers have also employed nuclear power; as of 2006, the only ones remaining in service are the Russian Kirov class. An example of a non-military ship with nuclear marine propulsion is the Arktika class icebreaker with 75,000 shaft horsepower. Commercial experiments such as the NS Savannah proved uneconomical compared with conventional propulsion.

[edit] Reciprocating diesel engines

About 99% of modern ships use diesel reciprocating engines[citation needed].
The rotating crankshaft can power the propeller directly (with slow
speed engines), via a gearbox (with medium and high speed engines) or
via an alternator and electric motor (in diesel-electric vessels).

The reciprocating marine diesel engine first came into use in 1903 when the diesel electric rivertanker Vandal was put in service by Branobel.
Diesel engines soon offered greater efficiency than the steam turbine,
but for many years had an inferior power-to-space ratio.

Diesel engines today are broadly classified according to

  • Their operating cycle: two-stroke or four-stroke.
  • Their construction: Crosshead, trunk, or opposed piston.
  • Their speed.
    • Slow speed: any engine with a maximum operating speed up to 300
      revs/minute, although most large 2-stroke slow speed diesel engines
      operate below 120 revs/minute. Some very long stroke engines have a
      maximum speed of around 80 revs/minute. The largest, most powerful
      engines in the world are slow speed, two stroke, crosshead diesels.
    • Medium speed: any engine with a maximum operating speed in the
      range 300-900 revs/minute. Many modern 4-stroke medium speed diesel
      engines have a maximum operating speed of around 500 rpm.
    • High speed: any engine with a maximum operating speed above 900 revs/minute.

Most modern larger merchant ships use either slow speed, two stroke,
crosshead engines, or medium speed, four stroke, trunk engines. Some
smaller vessels may use high speed diesel engines.

The size of the different types of engines is an important factor in
selecting what will be installed in a new ship. Slow speed two-stroke
engines are much taller, but the area needed, length and width, is
smaller than that needed for four-stroke medium speed diesel engines.
As space higher up in passenger ships and ferries is at a premium,
these ships tend to use multiple medium speed engines resulting in a
longer, lower engine room than that needed for two-stroke diesel
engines. Multiple engine installations also give more redundancy in the
event of mechanical failure of one or more engines and greater
efficiency over a wider range of operating conditions.

As modern ships" propellers are at their most efficient at the
operating speed of most slow speed diesel engines, ships with these
engines do not generally need gearboxes. Usually such propulsion
systems consist of either one or two propeller shafts each with its own
direct drive engine. Ships propelled by medium or high speed diesel
engines may have one or two (sometimes more) propellers, commonly with
one or more engines driving each propeller shaft through a gearbox.
Where more than one engine is geared to a single shaft, each engine
will most likely drive through a clutch, allowing engines not being
used to be disconnected from the gearbox while others keep running.
This arrangement lets maintenance be carried out while under way, even
far from port.

[edit] Gas turbines

Many warships built since the 1960s have used gas turbines for propulsion, as have a few passenger ships, like the jetfoil. Gas turbines are commonly used in combination with other types of engine. Most recently, the Queen Mary 2 has had gas turbines installed in addition to diesel engines.
Due to their poor thermal efficiency at low power (cruising) output, it
is common for ships using them to have diesel engines for cruising,
with gas turbines reserved for when higher speeds are needed. Some
warships and a few modern cruise ships have also used the steam
turbines to improve the efficiency of their gas turbines in a combined cycle,
where wasted heat from a gas turbine exhaust is utilized to boil water
and create steam for driving a steam turbine. In such combined cycles,
thermal efficiency can be the same or slightly greater than that of
diesel engines alone; however, the grade of fuel needed for these gas
turbines is far more costly than that needed for the diesel engines, so
the running costs are still higher.

[edit] Group terminology

Ships may occur collectively as fleets, squadrons, flotillas, or convoys. A collection of ships for military purposes may compose a navy, task force, or an armada. In the past, people counting or grouping disparate types of ship may refer to the individual vessels as bottoms,
but this generally refers only to merchant vessels. Groups of sailing
ships could constitute a fleet of ___ sail (e.g., "a fleet of 40
sail"). Groups of submarines (particularly German U-boats in the 1940s) formerly hunted in wolf packs.


Measuring ships

One can measure ships in terms of overall length, length of the waterline, beam (breadth),
depth (distance between the crown of the weather deck and the top of
the keelson), draft (distance between the highest waterline and the bottom of the ship) and tonnage.
A number of different tonnage definitions exist and are used when
describing merchant ships for the purpose of tolls, taxation, etc.

In Britain until Samuel Plimsoll"s Merchant Shipping Act, 1876,
ship-owners could load their vessels until their decks were almost
awash, resulting in a dangerously unstable condition. Additionally,
anyone who signed onto such a ship for a voyage and, upon realizing the
danger, chose to leave the ship, could end up in jail.

Samuel Plimsoll, a Member of Parliament, realised the problem and engaged some engineers to derive a fairly simple formula to determine the position of a line on the side of any specific ship"s
hull which, when it reached the surface of the water during loading of
cargo, meant the ship had reached its maximum safe loading level. To
this day, that mark, called the "Plimsoll Line", exists on ships" sides, and consists of a circle with a horizontal line through the centre. On the Great Lakes of North
America the circle is replaced with a diamond. Because different types
of water, (summer, fresh, tropical fresh, winter north Atlantic) have
different densities, subsequent regulations required painting a group
of lines forward of the Plimsoll mark to indicate the safe depth (or
freeboard above the surface) to which a specific ship could load in
water of various densities. Hence the "ladder" of lines seen forward of
the Plimsoll mark to this day. This is called the "freeboard mark" or "load line mark"in the marine industry.


Nomenclature

Main parts of ship. 1: Chimney; 2: Stern; 3: Propeller; 4: Portside; 5: Anchor; 6: Bulbous bow; 7: Bow; 8: Deck; 9: Superstructure.
Main parts of ship. 1: Chimney; 2: Stern; 3: Propeller; 4: Portside; 5: Anchor; 6: Bulbous bow; 7: Bow; 8: Deck; 9: Superstructure.

A ship usually has enough size to carry its own boats, such as lifeboats, dinghies, or runabouts. A rule of thumb used is "a boat can fit on a ship, but a ship can"t fit on a boat". Consequently submarines are referred to as "boats", because early submarines were small enough
to be carried aboard a ship in transit to distant waters (even though
modern submarines could probably fit small boats aboard, tradition
dictates they are always referred to as "boat"). Other types of large
vessels which are traditionally called boats are the Great Lakes freighter, the riverboat, and the ferryboat.
Though large enough to carry their own boats and/or heavy cargoes,
these examples are designed for operation on inland or protected
coastal waters. Often local law and regulation will define the exact size (or the number of masts) which a boat requires to become a ship. Nautical means related to sailors, particularly customs and practices at sea. Naval is the adjective pertaining to ships, though in common usage it has come to be more particularly associated with the noun "navy."